Kinetics and mechanism of the oxidation of amino acids by peroxomonosulphate oxidation of β-phenylalanine,isoleucine and threonine

The kinetics of oxidation of amino acids (AA) by peroxomonosulphate (PMS) in the presence and absence of formaldehyde were studied. Analysis of the results shows that the rate can be represented as, at constant [H⁺]and in the absence of formaldehyde

In the presence of formaldehyde and at constant [H⁺]the rate law is

Perusal of the kinetic results show that the formaldehyde catalysed reaction occurs $\text{\$}\text{?}$10⁵ times faster than uncatalysed and this is attributed to the formation of Schiff base. Mechanism of the reaction is discussed in terms of kinetic results.     

Polymerization of acrylamide in the presence of ultrasound and peroxomonosulfate

Polymerization of acrylamide (M) in the presence of ultrasound and peroxomonosulfate (PMS) was carried out for the first time for various concentration ranges of monomer and initiator and various temperatures at a constant frequency of 1 Mhz. The rate of polymerization R_p was found to increase with increase in the concentration of monomer and initiator and found to depend on [M] and [PMS]^1/2. The rate of disappearance of initiator (-d[PMS]/dt) was also followed simultaneously under the experimental conditions and found to increase linearly with increase in [PMS]. A probable reaction mechanism was proposed on the basis of the observed results, and the individual rate constant were evaluated. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2715–2719, 1998     

Ingenious bioorganic adsorbents for the removal of distillery based pigment-melanoidin: preparation and adsorption mechanism

Melanoidins are composite biopolymers which consist of amino carbonyl compounds which are the major coloring and polluting elements of distillery effluent. In this study, a synthetic melanoidin was used as a model for natural melanoidins, the chief colorant of the effluent. Deportations of melanoidins were investigated using both natural adsorbents and constructed microbial consortia based adsorbents and denoting it using the adsorption isotherms and SEM analysis. A review enabled us to assess about the valuation of the prepared low cost adsorbent and microbial coated adsorbents and for the treatment of the synthetic melanoidin solution. Based on the performances, both Microbial Coated Commercially Activated Carbon (MCCAC) and Commercially Activated Carbon (CAC) were better when compared with the other adsorbents at lower melanoidin concentrations; however, at higher melanoidin concentration, MCCAC performed better. The utilization of CAC for the removal of melanoidins may be cost competitive; hence Microbial Coated Procured Prosopsis Activated Carbon (MCPPAC) can be used as a substitute for the removal systems. Therefore, the microbial coated adsorbents can be a remedy for the removal of color through expatriation of melanoidin from the distillery effluents.     

Mechanism of the azide–bromine reaction in aqueous medium

Results on the oxidation of N by Br₂ in neutral and acid media are presented. The rate of the reaction is found to be proportional to [N] and [Br₂]. The gaseous product of oxidation is found to be pure nitrogen. The stoichiometry of the reaction is The reaction shows a positive salt effect. It is found that the addition of Br^? stabilizes the complex BrN₃, which decomposes into Br^? and N₂: The spectroscopic measurements also support the kinetic observation. The equilibrium constant K, the rate constants and the thermodynamic parameters were calculated. It is observed that H⁺ ion inhibits the reaction. The mechanism is discussed in terms of the kinetic results.     

Construction of a Low Cost Photoacoustic Spectrometer for Characterization of Materials

During the past few years, another optical technique has been developed to study those materials, which cannot be studied, by the conventional transmission or reflection techniques. The present technique called Photoacoustic spectroscopy or PAS is different from the conventional techniques chiefly in that the interaction of the incident energy of the photons with the materials under investigation is studied not through subsequent detection and analysis of some of the photons, but rather through a direct measure of the energy absorbed by the material. The aim of this presentation is to highlight the construction of a simple Photoacoustic spectrometer which can easily be constructed even in high school and college laboratories with the available low cost but efficient components and use it for characterization of solid (opaque or transparent), liquid and gas samples under investigations. The essential parts of the photoacoustic spectrometer designed in the laboratory (MADURAI – PA SPECTROMETER), consists of three main components.The total cost comes around 900 Euros. It is an affordable cost for researchers working with paucity of funds and facilities and many constraints especially in the developing countries. In the next few years we aim to study material characterization using MADURAI –PA SPECTROMETER.     

Kinetics of oxidation of carbonyl compounds by peroxomonosulfate. Formaldehyde, formic acid and formate anion

Kinetics of oxidation of formaldehyde, formic acid and formate anion by peroxomonosulfate (PMS) were studied. Formaldehyde is oxidized both by HSO ₅ ^– and SO ₅ ^2– , whereas formic acid and formate ion are oxidized by SO ₅ ^2– alone. The kinetic results show that the formaldehyde is 10³ times more reactive than formic acid, which in turn reacts 10² times faster than formate anion. Mechanisms are discussed in terms of the kinetic results.

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